Field of the Invention
The present invention relates to an image forming apparatus, such as a copier and a printer, that includes a function to form an image on a recording material, such as a sheet of paper.
Description of the Related Art
An electrophotographic system has been used for an image forming apparatus, such as a copier and a page printer. In an electrophotographic system, a toner image formed on a photosensitive drum (image bearing member) is transferred onto a recording material, such as paper, using electrostatic force, and the toner image is melted and adhered (fixed) onto the recording material by heat and pressure applied by a fixing unit, whereby the image is formed on the recording material. Recently high level functions, that involve color and high speed, have been used in electrophotographic type image forming apparatuses, and a color image forming apparatus based on an electrophotographic process having an intermediate transfer belt is widely used to support these high level functions.
A concern of such an image forming apparatus is that if the photosensitive drum is constantly in contact with the intermediate transfer belt, the surface of the photosensitive drum wears by the contact with the intermediate transfer belt.
A proposal to solve this problem is a configuration to minimize the abrasion of the photosensitive drum by separating a belt portion of the intermediate transfer belt, which faces the photosensitive drum that does not perform the image forming operation, away from the photosensitive drum when the intermediate transfer belt is cleaned or when a monochrome image is formed (Japanese Patent Application Laid-open No. H10-207151).